How do you remove the overlap of two mirrored, hollow, conical, cylinders?
Create a bottomless cone object centered around the midpoint between the two cones.
In Edit Mode move all the geometry to one side the required distance so the cone is centered on the eye.
Now add a Mirror Modifier to the cone and turn off clipping. Activate bisecting for the X axis (or whatever orientation fits your particular model) and it will cut the cones at the bisecting plane.